Today, customers can interact with your storefront in various digital places--desktop, mobile, and tablet--and expect experiences tailored to where they do so. You can no longer simply build a website and assume your digital job is done.

Here's how to build a digital strategy that makes sense across platforms:

1. Understand your customers.Start by learning everything possible about who your customers are and how they use your product or service. Do one-on-one research, in-depth interviews in your customer's own environment, and follow-up surveys to quantify trends and "technographic" information. Some good questions to ask: Who is the user? What device does he or she own? What content do she want? What is she trying to do? Where and when does she want to access your brand, or information about it?

2. Meet expectations.To delight customers, take advantage of the unique capabilities and promise of each device. You'll disappoint if you simply replicate your website on all platforms. On mobile phones, users want information lightning fast because they're on-the-go. They appreciate concise, pared down information. They usually perceive apps as faster than mobile sites, and like to tie in to other apps for GPS location awareness and personalization like contacts and photos. Our studies show that for users tablets are "like a laptop, but for more simple tasks." They like to navigate like they do on a desktop, but with more swipes, flicks, and less scroll and click. They like apps to have a deeper experience than a website, with more immersive rich-media and social integration, as well as customization and personalization.

3. Determine content for desktop, mobile and tablet.If you discover that your customers largely want the same information across desktop, mobile, and tablet, you should consider an approach called "responsive design," which helps easily adapt the same content for the device on which it is viewed. This is, for instance, what Johnson & Johnson does. But, if you learn that the context largely drives different tasks, tools, and content per platform, then you’ll need to develop entirely different experiences. In recent research we did for a Fortune 500 company, we found customers need an on-the-go locator tool in a mobile version that's much less necessary in the desktop one.

4. Prototype, prototype, prototype.Test out your designs across each device before you launch. It costs up to 10 times more to solve a site or app problem after launch and can result in huge opportunity costs if customers are unable to do what they want once you're live. Invest time in getting customer feedback mid-way in the development process. Also, always use an iterative testing process--test day one, make changes day two, test day three, and on—to confirm suggest changes solve identified problems; don't just hope for the best after one testing round.

5. Observe your customers in the wild.Once you launch your digital strategy across desktop, mobile, and tablet devices, I recommend you watch your customers use them as they ordinarily do in their normal routines to continue to optimize them going-forward. In one case, a major bank used insights from an AnswerLab cross-platform ethnographic study to help tailor features by device. In this particular study, the bank learned that personal financial complexity--not age or tech-savvy--drove customer needs.